People with common variable immunodeficiency (CVID) are unable to make antibodies to fight infections. In addition to problems fighting infections, people with CVID have an increased risk of cancer. The reasons for the increased incidence of cancer in people with CVID are unknown. This study is designed to determine if patients with CVID are infected more frequently with a recently discovered virus called Human Herpes Virus 8 (HHV-8). Recent studies suggest that HHV-8 infection may cause certain cancers, especially in people with impaired immune responses. HHV-8 induced cancers are treatable with antiviral drugs. Therefore, it is important to determine if HHV-8 infection can lead to cancer in people with CVID. We have collected blood and saliva samples in 15 people with CVID. We are now in the process of screening these specimens for HHV-8 infection.